[Microsoft Project]: Resource vacation effect on task duration RRS feed

  • Question

  • When setting vacation to a resource , duration changes automatically , while I need duration to still fixed, this doesn't make me feel comfortable.

    All I need is to decrease work of task , after setting vacation , while keeping duration fixed.

    Is it feasible ? any workaround ?

    Thanks for your support.

    Sunday, December 1, 2019 7:38 AM

All replies

  • YasserKonsowa,

    By default, tasks are set up as fixed work so when you change a resource's assignment (e.g. vacation) the duration will change. What you want to do is to set the task type to fixed duration. Then when you change the assignment, work will also change.

    Project's basic work equation is:

    Duration = Work/Units

    Hope this helps.


    Sunday, December 1, 2019 4:42 PM
  • Yes , I already set the task to fixed duration , then when I set vacation to a resource , I expect the work to decrease,

    but what happens, MS project automatically shifts the project start date , to keep same duration , which I don't need to happen.

    I want it to affect only the work.

    Hope it is clear enough ,

    Thanks for your support. 

    Wednesday, December 4, 2019 9:14 AM
  • YasserKonsowa,

    In most cases Project is only a tool, it does not make "decisions" by itself. However, there is a case (this one) wherein Project makes a unilateral decision that work trumps (i.e. has a higher "value" than) duration. Even though a task is set as fixed duration, once a resource is assigned, a later change to that assignment will in fact cause Project to change the task duration to maintain the original work. The user is given a warning but there is no "opt-out" as there is with come other types of changes.

    So why does Project do this? Consider that performance of work accomplishes something but the simple passing of time (duration) does not by itself accomplish anything. Therefore when there is a change to one of the variables in Project's work equation (i.e. Duration=Work/Units), preserving the value of work supersedes preserving duration. If for some reason, the user DOES want to preserve duration, a second step is required.

    How does all this relate to your scenario? Let's say Joe is assigned to a task that must be completed in a week (5 day duration). The work to accomplish this task is estimated at 20 hours, meaning that sometime during the one week period Joe must perform 20 hours of work. When initially set up as a fixed duration task, Project will linearly spread the 20 hours over the full 5 day duration (i.e. 4 hours per day). Now let's say that Joe needs to take a vacation day during the week so his resource calendar is changed to have one day off. Project responds by saying the resource is assigned outside the duration and therefore the duration will be changed to accommodate the changed assignment. No option to disagree, the unilateral decision is being made by Project. And why is that? The original work content was estimated at 20 hours, so unless the estimate was way off or there is an actual change in scope of the work, the 20 hour work content must be maintained and the only way to do that is to extend the duration. If appropriate, the work content can then be manually reduced to 16 hours. Why 16 hours and not 12 hours since the resource is taking a full day off? Remember, Project linearly spread the 20 hours work over the full 5 days, which means the resource is assigned at 50%, or 4 hours per day. When the adjustment in work is made, Project will ask if the duration should be reduced or if the work should be re-spread to maintain the extended duration.

    I know, a rather long explanation but there is some logic behind a fixed duration task not staying "fixed duration" when changes are made after the task is initially set up.

    Hope this helps.


    Thursday, December 5, 2019 4:27 PM